Polyethylene of Raised Temperature Resistance (PE-RT) Nanocomposites Reinforced with Graphene Oxide for Application in Flexible Pipelines

Polyethylene of Raised Temperature Resistance (PE-RT) is a specially designed high-density polyethylene utilizing bimodal resin technology. It is suitable for oil and gas pipeline applications, exhibiting excellent long-term creep resistance at elevated temperatures. Flexible risers require security against potential offshore oil leaks, prompting the reinforcement of PE-RT with graphene oxide (GO) at concentrations of 0.5, 1.0, and 2.0 wt.%. The nanocomposites were processed in a twin-screw mini extruder at 180°C, with a screw speed of 100 rpm and a residence time of 6 min. The results indicated an increase in the thermal stability of the nanocomposite by 14°C. XRD and DSC analyses revealed a higher crystallinity index for the sample with the lowest GO content. The water contact angle values increased from 98° in the pure matrix to 102° in the nanocomposite, suggesting a slight increase in the material's hydrophobicity due to nanoparticle incorporation. SEM images demonstrated a good interface between GO nanoparticles and PE-RT without agglomeration. The Shore D hardness increased from 50 to 59 with 2.0 wt.% GO. Although the 0.5 wt.% GO composition exhibited a higher degree of crystallinity, other properties such as thermal resistance, Shore D hardness, contact angle, dispersion, and homogeneity tended to improve with increasing nanoparticle content. Consequently, it can be concluded that the optimal concentration of GO in the PE-RT matrix is approximately 1.0 wt.%. Incorporating 1.0 wt.% GO resulted in an increase in Young's modulus from 335 ± 37 MPa to 409 ± 42 MPa, indicating enhanced mechanical strength of PE-RT. Finally, aging tests showed that GO reduced the swelling degree of the final material, suggesting that PE-RT/GO is a promising candidate for pipeline applications.

Keywords:
Polyethylene of Raised Temperature Resistance (PE-RT); graphene oxide; nanocomposites; nanotechnology